Totally Aerated Combustion Burner

ABSTRACT

The air-fuel mixture permeable member is disposed to overlap that surface of the burner frame which lies opposite to the burner body. The fixing frame is disposed so as to be fixed to the inner peripheral portion of the enclosing frame part of the burner frame by pinching the air-fuel mixture permeable member between the inner peripheral portion and the fixing frame. The air-fuel mixture permeable member has an extended part protruding outward beyond the fixing frame so as to cover by this extended part an outer peripheral portion of the enclosing frame part.

TECHNICAL FIELD

The present invention relates to a totally aerated combustion burner having a burner body which is supplied inside thereof with an air-fuel mixture, and a combustion plate part which covers an open surface of the burner body and through which the air-fuel mixture is ejected.

BACKGROUND ART

As this kind of totally aerated combustion burner, there is known in patent document 1 an arrangement in which the combustion plate part is made up of; a burner frame having in a central part thereof an air-fuel mixture passage region and an enclosing frame part around the air-fuel mixture passage region; and a member permeable to the air-fuel mixture (hereinafter called “an air-fuel mixture permeable region”), the air-fuel mixture permeable member which is made of heat-resistant fibers and which covers the air-fuel mixture passage region of the burner frame. In this arrangement, the burner frame is of a picture frame and has a single opening in the air-fuel mixture passage region for the air-fuel mixture to pass therethrough.

In addition, according to the above-mentioned arrangement, in order to prevent the burner frame from getting overheated by heating with convection and radiation heat from the flame to be formed by the combustion of the air-fuel mixture ejected from the air-fuel mixture permeable member, the enclosing frame part of the burner frame is provided with a thermal insulation material in order to cover the enclosing frame part from the side opposite to the burner body. By the way, the thermal insulation material is fixed by a fixing frame that is spot-welded in advance to that surface of the enclosing frame part which is opposite to the burner body.

However, in the above-mentioned arrangement, the fixing frame and the thermal insulation material are required, bringing about an increase in the number of parts. Also a step of assembling the thermal insulation material becomes necessary, resulting in an obstacle to an attempt to reduce the cost.

PRIOR ART DOCUMENTS Patent Documents

-   Patent Document 1: JP2017-116160A

SUMMARY Problems that the Invention is to Solve

In view of the above points, this invention has a problem in providing a totally aerated combustion burner in which the thermal insulation material for preventing the overheating of the burner frame is not necessary so as to be able to attempt a cost reduction.

Means for Solving the Problems

In order to solve the above-mentioned problem, this invention is a totally aerated combustion burner comprising: a burner body which is supplied inside thereof with an air-fuel mixture; and a combustion plate part which covers an open surface of the burner body and through which the air-fuel mixture is ejected. The combustion plate part is made up of: a burner frame having in a central part thereof an air-fuel mixture passage region and an enclosing frame part around the air-fuel mixture passage region; and an air-fuel mixture permeable member which is made of heat-resistant fibers and which covers the air-fuel mixture passage region of the burner frame, the air-fuel mixture passage region of the burner frame having formed a single opening or a plurality of openings for the air-fuel mixture to pass therethrough. The air-fuel mixture permeable member is disposed to overlap that surface of the burner frame which lies opposite to the burner body. The combustion plate part further comprises a fixing frame which is fixed to that inner peripheral portion of the enclosing frame part of the burner frame which is closer to the air-fuel mixture passage region, in a manner to sandwich the air-fuel mixture permeable member between the inner peripheral portion of the enclosing frame part of the burner frame and the fixing frame. The air-fuel mixture permeable member has an extended part protruding outward beyond the fixing frame so that the extended part covers that outer peripheral portion of the enclosing frame part which is positioned outside the fixing frame.

The air-fuel mixture permeable member is made of heat-resistant fibers and contains therein an air space (cavity). According to this invention, that extended part of the air-fuel mixture permeable member which protrudes beyond the fixed frame functions as a thermal insulating material. Therefore, the burner frame can be effectively prevented from getting overheated. In addition, according to this invention, since there is no need of separately preparing a thermal insulation material, the cost can be reduced.

In this invention, a clearance shall preferably be secured between the outer peripheral portion of the enclosing frame part and the extended part of the air-fuel mixture permeable member. According to this arrangement, due to the presence of the air space inside the clearance, the thermal insulation property relative to the burner frame can be more improved. By the way, if the outer peripheral portion of the enclosing frame part is provided with a plurality of projected parts at a circumferential distance from one another so as to secure the clearance by coming into contact with the extended part of the air-fuel mixture permeable member, the above-mentioned air space can advantageously be stably secured.

By the way, the heat-resistant fibers that are the material of the air-fuel mixture permeable member can be made of metal fibers, but the metal fibers are high in thermal conductivity, resulting in a decrease in insulation characteristics. On the other hand, if the air-fuel mixture permeable member is made of non-metal heat resistant fibers such as SiC and the like, the thermal conductivity of the heat-resistant fibers becomes low. As a consequence, the heat insulation property by the extended part of the air-fuel mixture permeable member can be sufficiently secured.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a combustion apparatus equipped with a totally aerated combustion burner according to a first embodiment of this invention.

FIG. 2 is a perspective view of the combustion apparatus as viewed from a side opposite to that in FIG. 1.

FIG. 3 is a sectional view cut away along the line III-III in FIG. 1.

FIG. 4 is a sectional view cut away along the line IV-IV in FIG. 3.

FIG. 5 is a perspective view in an exploded state of the totally aerated combustion burner according to the first embodiment.

FIG. 6 is an enlarged sectional view of an essential part in an assembled state of the combustion plate part in FIG. 5.

FIG. 7 is an enlarged sectional view of an essential part, corresponding to FIG. 5, of the combustion plate part of the totally aerated combustion burner according to a second embodiment.

PREFERRED EMBODIMENTS FOR CARRYING OUT THE INVENTION

A combustion apparatus shown in FIGS. 1 through 4 is provided with: a totally aerated combustion burner 1 according to an embodiment of this invention, the burner 1 having a burner body 11 which is supplied inside thereof with air-fuel mixture (mixture gas of fuel gas and primary air), and a combustion plate part 12 which covers a downward open surface 111 of the burner body 11; and a combustion box 2 having a box flange part 22 at an upper end thereof, the box flange part 22 being fastened with screws 21 to a body flange part 112 enclosing an open surface 111 of the burner body 11. The combustion box 2 has housed therein a heat exchanger 3 for hot water supply.

The heat exchanger 3 is constituted by a fin-tube type of heat exchanger provided with a multiplicity of fins 31 and a plurality of heat-absorbing tubes 32 which penetrate these fins 31. On an outside surface of side plate 23, 24 on laterally one side and the opposite side, respectively, of the combustion box 2, there are provided a plurality of connection covers 33 which define connection passages of the adjacent two heat absorbing tubes 32, 32 between each of the side plates 23, 24. In this manner, all the heat-absorbing tubes 32 are connected together in series with one another. Further, the connection cover 33 defining the connection passage, which is connected to the heat absorbing tubes 32 on an upstream end of the heat exchanger 3, between the side plates 24 of the laterally opposite side are provided with a water inlet 34.

Furthermore, on an inside of that portion of a rear-side side plate 25 of the combustion box 2 which is above the heat exchanger 3, there are disposed vertically arranged three pieces of first water passages 5 ₁ made up of tubes in a manner to contact the side plate 25. Also on an inside of that portion of a front-side side plate 26 of the combustion box 2 which is above the heat exchanger 3, there are also disposed vertically arranged three pieces of third water passages 5 ₃ made up of tubes in a manner to contact the side plate 26. In addition, on an outside surface of the laterally one-side side plate 23 of the combustion box 2, there are connected: an inlet-side header cover 51 defining, together with the side plate 23, a connection passage which connects the vertically disposed three pieces of first water passages 5 ₁ to the heat absorbing tube 32 on a downstream end of the heat exchanger 3; and an outlet side header cover 52 defining, together with the side plate 23, a connection passage for the vertically arranged three pieces of third water passages 5 ₃. The outlet side header cover 52 is provided with a hot water outlet 53.

Furthermore, as shown in FIGS. 2 and 3, the laterally opposite-side side plate 24 of the combustion box 2 is provided with second water passages 5 ₂ which connect the rear side first water passages 5 ₁ and the front side third water passages 5 ₃. Each of the second water passages 5 ₂ is made up of: a laterally inward dent which is formed in the side plate 24; and a cover 54 which is mounted on an outside surface of the side plate 24 in a manner to cover the dent. It is thus so arranged: that the water to be supplied from the water inlet 34 is heated by the heat exchanger 3; and that the heated water flows out of the hot water outlet 53 through the connection passage inside the inlet-side header cover 51, the first water passages 5 ₁, the second water passages 5 ₂, the third water passages 5 ₃, and the connection passage inside the outlet-side header cover 52. In addition, the laterally one-side side plate 23 of the combustion box 2 is provided with a fourth water passage 54 which extends rearward, from an upper portion, of the connection passage inside the outlet-side header cover 52, the fourth water passage 54 being constituted by: a laterally inward dent which is formed in the side plate 23; and a cover 52 a which covers this dent and which is integral with the outlet-side header cover 52. It is thus so arranged that each of the side plates 23-26 of the combustion box 2 is cooled by the water which flows through these first through fourth water passages 5 ₁-5 ₄.

Further, the front-side side plate 26 of the combustion box 2 has mounted thereon electrode parts 6 having an ignition electrode 61, a grounding electrode 62, and a flame rod 63 which are protruded through the side plate portion between the two, i.e., the first and the second from the top, of the third water passages 5 ₃, 5 ₃ into the combustion box 2. The electrode parts 6 are additionally provided with an inspection window 64 through which the inside of the combustion box 2 can be visually inspected.

Detailed description will now be made of the totally aerated combustion burner 1. The burner body 11 has opened therethrough an inlet port 113 for connecting thereto a fan 4 which supplies air-fuel mixture. The inlet port 113 has mounted thereon a check valve 13 which prevents the air-fuel mixture remaining inside the burner body 11 from flowing backward to the side of the fan 4, at the time of stopping of the fan 4. The check valve 13 is made up of; a resin-made valve box 131 which is built into the inlet port 113; and a resin-made valve plate 132 which is rotatably mounted, so as to be opened or closed, in that opening of the valve box 131 which faces inward of the burner body 11.

With reference also to FIGS. 5 and 6, the combustion plate part 12 is made up of; a burner frame 121 of a sheet-metal make, having in a central part thereof an air-fuel mixture passage region 121 a, and an enclosing frame part 121 b around the air-fuel mixture passage region 121 a, and an air-fuel mixture permeable member 122 made of heat-resistant fibers and which covers the air-fuel mixture passage region 121 a of the burner frame 121. The air-fuel mixture passage region 121 a of the burner frame 121 of this embodiment has formed therein a plurality of openings 121 a′ made up of small holes through which the air-fuel mixture passes. The air-fuel mixture permeable member 122 is constituted by a knit fabric or felted non-woven fabric of heat-resistant fibers, and is disposed so as to overlap that surface (lower surface) of the burner frame 121 which is on the side opposite to the burner body 11. The air-fuel mixture supplied into the burner body 11, after having passed through the openings 121 a′, permeates through the air-fuel mixture permeable member 122 for ejection to perform totally aerated combustion.

In an outer periphery of the enclosing frame part 121 b of the burner frame 121, there is formed a frame flange part 121 d, extended (or protruding) outward, including a stepped part 121 c that is bent toward the burner body 11 side (upward). In this arrangement, the frame flange part 121 d is sandwiched between the body flange part 112 and the box flange part 22, and further a packing 7 is interposed between the frame flange part 121 d and the body flange part 112, thereby securing sealing properties. By the way, as clearly shown in FIG. 4, the air-fuel mixture passage region 121 a and the enclosing frame part 121 b of the burner frame 121 are curved into an arcuate shape in cross section in the front-to-back direction. Similarly, the air-fuel mixture permeable member 123 is also curved into an arcuate shape in cross section in the front-to-back direction.

Now, in case overheating happens to the burner frame 121 due to the heating by convection and radiation heat from the flame to be formed by the combustion of the air-fuel mixture, when the heat transfers from the burner frame 121 to the burner body 11, the burner body 11 will be elevated to a considerably high temperature. As a consequence, a bad effect will be inflicted on the check valve 13 which is an accessory part to the burner body 11. In this case, in order to impede the heat transmission from the burner frame 121 to the burner body 11, it is considered to make the packing 7 of a ceramic packing that is superior in thermal insulation characteristics. This solution, however, brings about a higher cost. In order to enable to use an ordinary packing as the packing 7, it becomes necessary to prevent the burner frame 121 from getting overheated.

Therefore, in this embodiment, the combustion plate part 12 further comprises a fixing frame 123 which is fixed to an inner peripheral portion 121bin, near the air-fuel mixture passage region 121 a, of the enclosing frame part 121 b of the burner frame 121, in a manner to sandwich the air-fuel mixture permeable member 122 between the inner peripheral portion 121bin of the enclosing frame part 121 b of the burner frame 121 and the fixing frame 123. The fixing frame 123 is circular and is provided, at a circumferentially plurality of positions thereof, with drawn parts 123 a which protrude toward the burner frame 121 side (i.e., upward). In this arrangement, by inserting these drawn parts 123 a into each of holes 122 a formed in the air-fuel mixture permeable member 122, the drawn parts 123 a are then spot-welded to the inner peripheral portion 121bin of the enclosing frame part 121 b. The fixing frame 123 is thus fixed to the inner peripheral portion 121bin of the enclosing frame part 121 b. According to this arrangement, the air-fuel mixture permeable member 122 will be sandwiched between the enclosing frame part 121 b and the fixing frame 123 at a portion other than drawn parts 123 a of the fixing frame 123.

The air-fuel mixture permeable member 122 is provided with an extended part 122 b that protrudes outward beyond the fixing frame 123. It is thus so arranged that the extended part 122 b covers that outer peripheral portion 121bout of the enclosing frame part 121 b which is positioned outside the fixing frame 123. It is to be noted that the air-fuel mixture permeable member 122 is made of heat-resistant fibers and contains therein air space (cavity). Therefore, that extended part 122 b of the air-fuel mixture permeable member 122 which covers the outer peripheral portion 121bout of the enclosing frame part 121 b functions as the thermal insulation material. Overheating of the burner frame 121, specifically an excessive temperature rise of the frame flange part 121 d of the burner frame 12, can effectively be prevented. Therefore, it is not necessary to use, as the packing 7, an expensive one that is superior in thermal insulation property. Further, an insulation material need not be specially provided for the purpose of preventing the burner frame 121 from getting overheated, thereby contributing to the cost reduction.

By the way, it is also possible to replace the heat-resistant fibers as the material for the air-fuel mixture permeable member 122 with metal fibers. However, metal fibers are high in thermal conductivity and the thermal insulation property lowers. Therefore, the air-fuel mixture permeable member 122 shall preferably be made to be heat-resistant fibers of non-metal such as SiC and the like. According to this arrangement, since the thermal conductivity of the heat-resistant fibers becomes lower, thermal insulation property by the extended part 122 b of the air-fuel mixture permeable member 122 can advantageously be sufficiently secured.

Further, according to the second embodiment as shown in FIG. 7, the following arrangement may also be made, i.e., the extended part 122 b of the air-fuel mixture permeable member 122 is made to offset in a direction away from the burner frame 121 (i.e., downward) relative to the remaining portion of the air-fuel mixture permeable member 122 so that a clearance 124 may be disposed between the extended part 122 b and the outer peripheral portion 121bout of the enclosing frame part 121 b. According to this arrangement, due to the presence of the air space (cavity) in the clearance 124, the thermal insulation property relative to the burner frame 121 can all the more be improved. Furthermore, according the second embodiment, in the outer peripheral portion 121bout of the enclosing frame part 121 b, there are provided a plurality of projections 121 e which are intended to secure the above-mentioned clearance 124 as a result of abutment with the extended part 122 b of the air-fuel mixture permeable member 122. According to this arrangement, the above-mentioned clearance 124 can advantageously be stably secured.

Descriptions have so far been made of the embodiments of this invention with reference to the figures, but this invention shall not be limited to the above. For example, in the above-mentioned embodiments, the burner frame 121 has formed therein a plurality of openings 121 a′ made up of small holes. However, it is also possible to form a single opening over the entire region in the air-fuel mixture passage region 121 a. In this case, there may be arranged such that a distribution plate in which a plurality of small holes corresponding to the openings 121 a′ in the above-mentioned embodiment overlap that surface of the air-fuel mixture permeable member 122 which lies on the burner frame 121 side. In addition, in the above-mentioned embodiment, the burner frame 121 is made of a metal plate, it may alternatively be made of a material other than the metal plate such as made of aluminum die-cast product and the like. Further, the totally aerated combustion burner according to the above-mentioned embodiment is disposed such that the open surface 111 of the burner body 11 faces down. However, this invention is similarly applicable to the totally aerated combustion burner disposed such that the open surface 111 thereof faces up.

EXPLANATION OF MARKS

-   1 totally aerated combustion burner -   11 burner body -   111 open surface -   12 combustion plate part -   121 burner frame -   121 a air-fuel mixture passage region -   121 a′ opening -   121 b enclosing frame part -   121bin inner peripheral portion -   121bout outer peripheral portion -   121 e projected part -   122 air-fuel mixture permeable member -   123 fixing frame -   124 clearance 

1. A totally aerated combustion burner comprising: a burner body which is supplied inside thereof with an air-fuel mixture; and a combustion plate part which covers an open surface of the burner body and through which the air-fuel mixture is ejected, the combustion plate part being made up of: a burner frame having in a central part thereof an air-fuel mixture passage region and an enclosing frame part around the air-fuel mixture passage region; and an air-fuel mixture permeable member which is made of heat-resistant fibers and which covers the air-fuel mixture passage region of the burner frame, the air-fuel mixture passage region of the burner frame having formed a single opening or a plurality of openings for the air-fuel mixture to pass therethrough, wherein the air-fuel mixture permeable member is disposed to overlap that surface of the burner frame which lies opposite to the burner body; wherein the combustion plate part further comprises a fixing frame which is fixed to that inner peripheral portion of the enclosing frame part of the burner frame which is closer to the air-fuel mixture passage region, in a manner to sandwich the air-fuel mixture permeable member between the enclosing frame part of the burner frame and the fixing frame; and wherein the air-fuel mixture permeable member has an extended part protruding outward beyond the fixing frame so that the extended part covers that outer peripheral portion of the enclosing frame part which is positioned outside the fixing frame.
 2. The totally aerated combustion burner according to claim 1, wherein a clearance is secured between the outer peripheral portion of the enclosing frame part and the extended part of the air-fuel mixture permeable member.
 3. The totally aerated combustion burner according to claim 2, wherein the outer peripheral portion of the enclosing frame part is provided with a plurality of projected parts at a circumferential distance from one another so as to secure the clearance by coming into contact with the extended part of the air-fuel mixture permeable member.
 4. The totally aerated combustion burner according to claim 1, wherein the air-fuel mixture permeable member is made of non-metal heat-resistant fibers. 